The present invention relates to a cooling water pump with an internal rotor which is held in the housing and carries at least two impellers and with flow guide housings, namely an inflow housing and an outflow housing.
A number of boundary conditions must be observed in the design of cooling water pumps for internal combustion engines, particularly for motor vehicles. Such a cooling water pump must be simple in its design, cheap to produce and sufficiently sturdy in order to match the engine's service life without requiring any maintenance whatsoever. A further important criterion in the design of cooling water pumps is the restricted available installation space in modern motor vehicles. There is an additional problem in certain engines that high conveying quantities must be provided already at relatively low speeds. Moreover, the efficiency is to be as high as possible in order to reduce fuel consumption.
Usually, cooling water pumps are designed as radial centrifugal pumps whose dimensions are designed according to the volumes to be conveyed. Serious constructional problems can occur particularly when the outer diameter of the pump is limited.